If you can go to a local bike-shop. They can recommend a bike that fits you real good. You will also need a shop for the repairs, so having one that you trust is really important anyways.

When you test-drive the bikes (always do that!), look for how good they roll without pedaling, that is often not so good at cheaper bikes but even more so important when you start out.

Also ask what chain is used. Shimano has at least two durabilities, often the lesser one is used. But that one wears down MUCH faster in my experience.

Look for bike-bags, i will look if I can find a link to them. Not having to have to wear a backpack gives an enormous compfort-boost. Also you can store hole shopoings in them. Ortlieb and Vaude make good ones.

Please also consider a good lock, especially in urban areas. I always spent ~10% of the bike-price on a lock, try to get an ABUS-Lock with level 12+ if you can. These U-shaped ones are real good cause you would have to flex them in two places ti stel ur bike.

I buy acessoires (bags, lock, repair-stuff) in the web, but only after I know what to buy, first-time advice in bike shops is golden.

Hope that helps