Here's what I've put together. It is a sort of journey itinerary. It
is possible to do the above journeys in one day

:
Origin | Destination | Service | Origin Dep. | Dest. Arr. | Journey time |
====================================================================================================
Bicester North | London Marylebone | 1H25 0907 Banbury to London Marylebone | 0930 | 1032 | 62mins |
London Marylebone | Oxford* | 1T23 1035 London Marylebone to Oxford | 1035 | 1139 | 64mins |
Oxford | Bicester Village | 1Y33 1142 Oxford to London Marylebone | 1142 | 1156 | 14mins |
Bicester Village | Oxford** | 1T27 1135 London Marylebone to Oxford | 1223 | 1240 | 17mins |
Oxford | Bicester (Village)*** | 1Y41 1241 Oxford to London Marylebone | 1241 | 1255 |
* = First train out
** = Only option, no trains from other possible origin of Banbury
*** = Destination station not specified, Bicester Village only option anyway
====================================================================================================
Drive to Reading: 60 mins via A34 and A4074
====================================================================================================
Origin | Destination | Service | Origin Dep. | Dest. Arr. | Journey time |
====================================================================================================
Reading | Hayes & Harlington | 9P68 1322 Reading to London Paddington | 1322 | 1358 | 36mins |
Hayes & Harlington | Slough**** | 9R72 1343 London Paddington to Reading | 1403 | 1416 | 13mins |
Reading | Windsor & Eton Central | 2W28 1436 Slough to Windsor & Eton Central | 1436 | 1442 | 6mins |
Windsor & Eton Central | Slough***** | 2A28 1445 Windsor & Eton Central to Slough | 1445 | 1451 | 6mins |
Slough | Maidenhead****** | 2N40 1427 London Paddington to Didcot Parkway | 1452 | 1500 | 8mins |
Maidenhead | Marlow******* | 2B38 1534 Maidenhead to Marlow | 1534 | 1557 | 23mins |
**** = Go from Hayes & Harlington to Windsor & Eton Central via Slough, only option by train
***** = Go from Windsor & Eton Central to Marlow via Slough, only option by train
****** = Go from Slough to Marlow via Maidenhead, only option by train
******* = Go from Windsor & Eton Central to Marlow via Slough and Maidenhead, only option by train
====================================================================================================
Bus from Marlow to Henley-on-Thames: 28mins from Spittal Street
====================================================================================================
Origin | Destination | Service | Origin Dep. | Dest. Arr. | Journey time |
====================================================================================================
Henley | Twyford *8 | 2H49 1659 Henley-on-Thames to Twyford | 1659 | 1711 | 12mins |
Twyford | Reading *9 | 9R94 1628 London Paddington to Reading | 1719 | 1727 | 8mins |
Reading | Oxford | 1E64 1743 Reading to Newcastle | 1743 | 1808 | 25mins |
Oxford | Reading *10 | 1O24 1527 Manchester Piccadilly to Bournemouth | 1813 | 1842 | 29mins |
Reading | North Camp *10 | 1O84 1901 Reading to Shalford | 1901 | 1932 | 31mins |
North Camp | Reading *11 | 2V72 1843 Redhill to Reading | 1940 | 2017 | 37mins |
Reading | Swindon | 1C32 2002 London Paddington to Bristol Temple Meads | 2027 | 2056 | 29mins |
Swindon | Reading | 1L90 1958 Cheltenham Spa to London Paddington | 2102 | 2132 | 20mins |
*8 = Go from Henley to Oxford via Twyford, only option by train
*9 = Go from Twyford to Reading to get on train to go to Oxford (Henley to Oxford via Twyford & Reading is only option)
*10 = Go from Oxford to North Camp via Reading, only option by train
*11 = Go from North Camp to Swindon via Reading, only option by train
I hope this helps,
-Peter