Hi @Kerry7303
We have quite a few users who sell via eBay and other similar channels, so I’d definitely say QuickFile is suitable. I’ll give you some guidance on some of our features that could help, but you may find that other users would be better at this than what I am 
This can be done in a pretty straight forward set up - recording the purchase invoices on QuickFile. You’ll probably find it easier to add your eBay sales in bulk (e.g. recording your sales on a daily or weekly basis). As eBay themselves produce the invoices and confirmations for your purchasers, this should be sufficient backing evidence of where the money came from, should HMRC ever query anything.
We support multi-currency, so you can create your invoices in GBP or USD.
We have a feed with PayPal, so you can link your PayPal account and we’ll pull in your transactions from the previous day. This can actually automate the bulk invoicing mentioned above too.
You may find it easier to start fresh, but it’s not impossible to start from now. I’d recommend taking a look at our getting started tool which will give you some pointers is getting your accounts up and running.
I hope this helps, but please let me know if you have any further queries 