Lisa,
from a sole trader point of view if you have no other PAYE income you can earn a fair whack before having to declare it - £105 per week for National Insurance and £5345 as above for income tax. So you should be ok just selling a few ebooks. If things get more serious then you will need to complete an annual self assessment tax return and declare your income properly.
There is tax relief available for working form home and a lot of other bits and bobs however if your income is very small it probably wont be worth paying the likes of me to do your return for you as although we can provide "peace of mind" and "paper shuffling" we are unlikely to be able to justify our fees in terms of cash savings on your tax bill if you are at the £5-10k profit level as there simply isn't much to play with so you might end up doing this yourself which TBQH is not much worse than the children's tax credits form you have probably struggled with recently! There is help available from things like my book (
http://www.jamesesmith.co.uk/ebooks.htm sorry bad plug) which goes over basic record keeping and filing a small return for a self employed person.
On the banks, do watch out for the likes of Lloyds and what happens after the 18 month honeymoon period is over - ie big fees! Two offering not listed above are Abbey and BOS both have non-branch accounts which are free of charge beyond the first 18 months. I think the A&L one has a minimum deposit limit per month to stay free so watch out for that. NB I find ALL the banks are pretty poor and the only reason you get decent service is if you are lucky enough to have a good contact- who invariably moves on after a while, so its pot luck really.
Anyway good luck with the sales.
Regards,