I would also expect LX to be prepared to check the bags to final destination (if you show the TG ticket at check-in etc) however, you biggest obstacle will most likely be that by then you will not be allowed to enter Thailand. I bet in a few days you will not be able to complete these flights as you will not be allowed to board at LHR nor HKG. Good luck!
On a different note, why the hexx do you want to travel to Thailand now? (assuming that you are British/live in the UK)