The process and website for doing the VAT reclaim was refreshingly simple. I was actually really impressed with the whole process on the UKGOV website.
UKGOV website had one long alphabetical list of what you can claim, and what you can't. Also has an easy access portal to upload, with decent instructions.
Download/scan all invoices , title them one at a time ie... #1 LED BULBS BULBSTORE, #2 timber TIMBERSTORE etc
Make an excel list of them all, as you go through pulling out the required details from each invoice ... Ie BULBSTORE, vat number, claimable items, vat amount, totally amount etc into columns.
Upload them one line item at a time, and pull out the required info from your excel sheet.
Submit, and they ask for c 30% of the invoices to cross check, and upload them from your folder.
Very good system!