If you have properly stored old films that can use the original dev times but they are no longer on the Massive Dev Chart, one source that might be useful to you (it has been for me) is the archive.org version:
If you follow that link it will take you to the print version, which still works from the archive.org site. I think it's most useful for people using developers that are not just D-76 or Rodinal where the manufacturer may have included dev times in the packaging.
I initially went there to look at dev times for the original APX-400 in various developers. I have 100 ft of it frozen since 2011 and haven't shot any... which I should change
Key is, the film roll needs to be above the dew point (depends on humidity) all the way to the core, but without anyway to check the internal temperature, you need to leave it ou long enough so be sure it's warmed up enough. "Enough" is slippery -- if it's hot and very humid, it might be 22C or higher; if it's cold and dry (pretty sure Ireland doesn't have "dry"), it might be quite cool and still be okay.
Twenty-four hours is long enough for almost anything that doesn't contain a lot of water to get up to room temperature, which is presumed to be non-condensing conditions...