As stated the callsigns that don't use flight numbers change by season and are not published in advance. Some can be derived with some digging but don't wate your time trying to find a comprehensive list as it's very unlikely to be accurate.
e.g. TCX12YZ might be GLA-PMI this winter and be CWL-ALC for the summer. Given the time lag, libhomeradar and the others are often a season out in their routings. Bewarned, your sanity is at risk if you go down this path !
I sent in most of the winter ones to flightradar myself. Here is how i did it and will probably do for the summer ones (sorry for wording, might be bad)
1. Go onto flightradar24 and make sure you only have TCX / TOM aircraft on. I also need to go on flightstats.com
2. Track a plane which does not have its callsigns working.
3. Check its outbound flight, where it is flying from and to and name this for the route. (Eg, if TCX12WX was going from MAN - AGP i would write down that TCX12WX is from MAN - AGP)
4. Check its returning flight, should be the oposite to the outbound flight unless there is a swap. Write this down also.
5. Find the flightnumber using flightstats.com. If there are two flights on the day, check the UK flight departure or arrival and confirm this with flightradar24 playback.
I did this for the winter and the routes i have sent all seem to be correct
. Proof on flightradar.
The only routes with problems tend to be the ones over Egypt / Greece as there is no radar there
Another problem can be dodgey callsigns which do happen unfortunately