Northern Ireland based simple office services required - post a packet for me to UK mainland and then back to me in Ireland.

I have a technical component I need repaired in the UK. Post Brexit, there does not appear to be any process for doing this, other than a very involved system of registration of businesses. So I am looking for a reliable and trustworthy individual to help: 1. Receive ~500g small packet from me - open it to find stamped (paid royal mail) addressed package inside to forward to a UK address (a repair business in England). 2. Receive same ~500g packet back from the UK address 5 days later - open it to find stamped (paid royal mail) addressed package inside to forward onto me. I am based in the ROI. Looking for someone with their own address based in Northern Ireland (please send me a utility bill with your name and address on it to verify etc.).