Hi everyone, just thought I'd reopen this thread to give an update.
I ended up taking the good advice many of you offered me and, as soon as I passed my test, found a thirteen year old 1.4 Fiesta with 110k miles for £2600, it was relatively cheap to insure and has been a wonderful car so far.
It's fairly good on fuel economy and very comfortably does motorway speeds, has plenty of space and I haven't had any major issues with it yet, I did have the brake pads replaced but that's been it for maintenance. The clutch will probably have to be changed at some point but hopefully not until the MOT.
Thank you all very very much for the advice, I really appreciate it and it's probably saved me a lot of money over leasing a new vehicle!
You've made a good choice. Did you get some help, or was this just good fortune? I was definitely going to advise you to seek help of experienced people, as your OP read like you could have been ripped off easily. Not your fault, just the confidence of youth. You don't know what you don't know. No offence, but I have assumed you are a young person. Even if not, older person doesn't necessarily mean experienced car person.
Basics like whether a Fiesta does motorways fine, whether a new driver on a budget has the luxury of considering comfort (nope!), whether 10k a year is a lot, whether MoTs should bother you one bit, are all stuff that Old People pick up through bitter life experience. Be Wise, exploit your Elders. Rinse them for every scrap of advice. Ignore them if they drive a rust bucket. Keep doing it. Always more more learn, expensive mistakes to avoid.
There's nowt wrong with an old car as long as it's a reliable model - which Fiestas obviously are - it has been well looked after - which sounds about right at that average mileage if it's still economical - and you're not going to be thrashing it - which you obviously won't be.
As long as it hasn't got go faster stripes, a 1.4 Fiesta that old is never going to be too bad on insurance, even for a new driver. Be warned, don't make the mistake many newbies make and tell lies, even little white lies, on your application. They will make you pay for it, should you make a claim.
That said, you might want to research what you can do to better secure it, the locks/immobilizer probably aren't the best. Nobody's going to put much effort into stealing it other than idiot opportunists, but since any theft or damage would seriously mess up your life and your wallet, it's worth checking.
Now is the time to start cultivating relationships with mechanics, to save every penny you can. Find someone you trust, and reward them with regular business. Garages value repeat business most of all, but make sure to get second opinions discretely, or even educate yourself on the basics, to guard against being taken advantage of long term.
Don't insult their professionalism, but don't be an easy mark either. Never be afraid to ask questions, and speak up if you don't like or just don't understand the answer. Find out out what a new clutch for a Fiesta should cost, and how long it takes to fit it. Under no circumstances use high profile or even dealer garages. They really don't want your business and you can't afford it! But they will happily rinse you.
Hopefully you got basic roadside assistance included in your insurance, but if not, definitely get some. Nothing flashy, just the essentials, because with an older car like that, with your long drives, it's worth it even for one breakdown. A dodgy clutch, even more so. Don't wait to get that fixed either, you likely don't have the experience to know how long you can push it. Tip: if you find yourself rolling backwards during a hill start, you waited too long!
Last but not least, it may sound ridiculous, but do your best to keep it in good condition. Tyres, servicing, even basic cleaning. If things go well and you can afford an upgrade in a few years time, your low mileage will mean you still might be able to get back a nice little cash sum for your first car. The benefits of the current market (high demand, low supply).
On the flip side, do at least be prepared for serious but a little predictable bad luck. Your car, even that make, isn't bulletproof. They're small and cheap for a reason. Good running is not a foolproof indicator of future performance. Consult the manual for the major work ahead (always mileage based), and accept that bad luck sometimes means the engine explodes a good 30k miles before it should, and often right after you shelled out good money to replace expensive parts. Thems the breaks. For major work, always get a guarantee, but for a car that price and age, it's quite likely to be cheaper to scrap it and buy another.
With a fair wind though, it's the car after your second purchase that is the point you start to reap the benefits of age, wisdom and wages. Full roadside assistance. Extremely comfortable and powerful cars, for cheapish insurance. Dealer servicing. Courtesy cars.
Oh sweet Lord. How I wish I could relive those wonder years!
Good luck fella.