rear main crank seal leak is it worth repair ?

Its a 150k miller and otherwise just a handbrake fault on the MOT. These cars still fetch good money second hand so advice needed on the best course of action.
The garage say it could be 1500 pounds to fix the oil leak.

new parts this year were also..

2 new injectors I think they were called this year since it didn't start that fixed that issue.
new battery

Others may scoff, but replacing a crank seal at 150k is usually not worth the price. Unless it's a large leak and you plan on keeping it for many more miles.
I have been a car guy for over 50 years, and I am usually dead set against any oil additives. However, if the leak is a few drips overnight, Blue Devil Rear Main Seal Leak is your ticket.
I have owned Land Rovers for years and the joke is, if it's not leaking oil, it's empty. I have used it and the engine oil leak version for years, and it really works. Engine, transfer case, diffs.
Might give it a try - Bill