Drive to Iskenderun (you’ll need a carnet, so talk the camber of commerce) take ferry to port said expect 48 hours clearing customs, you may clear in 10 minutes but you may not, try to arrive there late on Wednesday as they like an empty impound on Fridays.
Drive to Suez, dump anything that may upset the Saudis unless your intending to eat / drink it on the ferry, then ferry to Jeddah.
Visa to Jeddah is easy enough.
Now the hard bit, visa to cross Saudi needs a sponsor, they are not easy to find as they take responsibility for you actions, but it is possible, you need to arrange this before you leave the UK and the Saudi embassy are actually quite helpful, but the reason for travel is likely to be your stumbling block, but there’s no reason the Saudis will object to football.
Youll be asked your route and it should avoid Mecca like the plaque go via Al Jumum to Az Zemah ( once in Saudi you can still use the 80/301 ) but avoid Mecca unless you have specific written permission.
Aim to hit Riyahd end of day 1, so stay at the customs impound overnight and start early, over night at Riyadh is easy enough and people will be helpful and friendly but observe local customs. Your western beliefs should be left in Bulgaria.
Next day drive to Salwa and cross the border into Qatar.
Job done but plan for delays, took me 11 days, paid bribes in Turkey and Egypt (all petty amounts) DO NOT TRY TO BRIBE IN SAUDI, just go with the flow and be patient, DO NOT express an opinion about anything, if you have women with you they MUST obey local custom.
coming back you’ll have lots more customs issues, especially when crossing the Bosphorus, try to cross Serbia in one day each way if possible,