-
Just one of those basic non digital ones is worth having to check how accurate the oven is from time to time.
A meat probe is always good to have also. Those ones James has look amazing but most digital probes will be good enough to do the job for oven cooking.
Generally a joint of meat can rest from 10 to 15 extra degrees over the time you take it out, depending on the grade you want and the temp cooked
So you should have an oven thermometer? Not to you specifically. Tho I used to go with two to see the oven temp difference in a gas oven.