Could be a problem with the stalk on the steering column not switching over to main beam - what happens if you try the main bean flash on the stalk?
Or there's maybe there's a problem with the high beam relay itself, related to the bulb blowing. The bad news here is that the relay is integral to the GEM module and not a serviceable part
I'll stand corrected on the relay part here. I remembered changing a relay for my full beams but this must have been on my MK1.