Hi Claire,
We do recommend that you separate your fixed assets, but if they are small value purchase's and similar items you could group these together, as long as you had a log just incase HMRC asked the question.
If they are of higher value, I would definitely suggest you separate these out.
With regards to the HP, not sure how familiar with Excel you are... on this spreadsheet it should be ok for you to add the lines you require (by right clicking on the number tab) when you have the lines you need, you will need to copy the formula's - drag the formula from I8 down the new lines, then again from J8 down, and lastly K8 down.
Let me know how you get on, and if you need further help, email me on
support@diyaccounting.co.uk
Regards
Louise