Be aware that a couple of mains-rated capacitors in the power supply don't age very well and it's almost a given that they should be replaced ASAP and before any further use of the computer.

https://www.retro-kit.co.uk/page.cfm/content/BBC-Micro-PSU-X...

I'd love to have a beeb to play with (I just missed the wave first time around - went from PET at school to PC at work), but they are going for silly prices on ebay. Maybe a garage or junk sale will turn up something!