I have a town bike and a mountain bike and would never thank anyone for choosing a bike for me. There are wheel sizes, frame sizes, handlebar widths, saddle types and reach parameters to consider, then there are brake types, handlebar shapes etc. With respect these need tailoring to the rider. Cycles on trains never seem to be a problem in cities but the trains in our area are usually full of cyclists and walkers so a bit of a problem at weekends in particular.
Someone suggested a Halfords voucher. I have never bought a bike from them but a friend did and he found the staff knowledgeable and very helpful. They often have some good bargains too apparently.
Another concern is the danger of cyclists wearing backpacks. There was a fatality locally when a backpack caused a rider to unbalance under the wheels of an artic. Panniers are much safer for moving things to and from uni. and they hold a vast amount of stuff. Good luck in your quest.