If I go to court will I have a criminal record
As others have said we have to assume from the document you uploaded you have been found guilty of a the ticketing offence (albeit without you knowing it) and have a fine, that is unpaid, and the criminal record that comes with that. This is why the Stat Dec process has been suggested as a way forward to 're-set' this - but be aware t
here is a time limit on making such a Stat Dec which starts the moment you became aware of all this - ie probably when the bailiffs tracked you down and you got that letter. So you do need to act quickly if you want to do that.
It's possible that you can get this sorted with advice from this forum, but given the nature of it (and if this has other serious consequences on you for example maybe future jobs, visas or some such) you do have the option of considering getting legal help from a solicitor about this.
There are a couple of legal firms that regularly get mentioned on this forum that people use, who specialise in rail fare evasion matters (can list them if that is of any interest eg to see if you can get a quote form them as to what their services cost), or you may be able to find a solicitor local to you who can deal with some or all of the aspects of this - eg the Stat Dec part of it.
The decision on what to do is of course up to you, and I would say the forum often suggests that for these cases the help of a solicitor is not required, but if you would feel more comfortable with getting help from one then I am sure people here can advise on how to find a suitable one.