Thanks @Greydog, I really appreciate your advice and all the detail!
Where do you get the copper crush washers from? Also, I’ll be purchasing the required tools as don’t have anything suitable (only worked on bicycles previously!) Would you recommend any particular online retailer for tools. I imagine I’ll be purchasing a fair few in the coming months as want to be able to do other servicing jobs including replacing brake discs and pads.
With regards to the oil, as you know you can get 5L and 1L bottles, can I get 2 x 5L and then keep the remainder for the next oil change, or does it not keep?
Thanks again!