Thanks for the advise guys, decided it was probably a job for a professional. I managed to source a second hand sump and got a mechanic round to do the changeover(all on Christmas Eve!) Just one issue, the replacement sump didn’t have a hole in it for the dipstick- the old one did?? Only found this out once the old sump was off and the new one was about to go on. I told old mate to crack on and fit it anyway. Apart from not being able to check how much oil is in there, am I risking anything else? I figure that whenever the check oil warning comes up I’ll just top her up a bit.
I will have to look at getting it sorted, but for the time being I’m dipstickless!