I would remove your existing headlights, buy the adjuster kit on ebay (make sure you get the one that contains 4 gear wheels per side, you'll need them!) and use a hairdryer to play on the edge of the plastic lens all round the light unit to soften the sealant, gently prying the lens away from the housing.
Once you can remove the lens, do so and then you can strip the old adjusters (or the remains of) out and fitr the new ones. To fit the adjuster drive gears, i used a 10mm socket to support the new gear and a deep 5.5mm 1/4" drive socket to push on the threaded part with a little silicone grease on the end of the threaded shaft to ease it into the new gear.
Once done, refit the reflector on the new adjusters, wipe any pawprints off the reflector with a microfibre cloth and put the lens in position ready to refit. Again heat up the sealant and work your way round heating, squeezing etc until the lens is completely refitted. After that i did a few "circuits" of the lamp unit with the hairdryer to make sure the sealant was even pressure on the lens and helped to spread it out/reseal.
Unless you do this outside in the pouring rain or inside a sauna, there's very little chance of introducing moisture and is ~£500 cheaper than new lights. Don't forget the adjusters are a common problem on these so even if you buy some secondhand ones with apparently good adjusters, chances are they will go again. Much better to revive your existing lights with the adjuster kit which is made from glass-flled nylon or similar (don't remember the exact plastic but it's one of the engineering plastics) so will likely outlast the car!
A timely squirt of silicone lube spray will help prevent the adjuster threads corroding and ease any adjustment necessary at MoT time.
PS - while my lenses were off, i gave them several good rubs with T-Cut to remove the small amount of oxidisation on them then a few coats of Turtle Wax polish to help potect them. Next year i will revisit this task and once happy they are completely clear, will use this instead of clear-coat lacquer/varnish to protect the lenses from going opaque agin :
https://www.ebay.co.uk/itm/151172691767
If it does go opaque (doubtful as it rejects 99% of UV) the film can simply be peeled off, the lenses rebuffed with T-Cut or similar and a new piece of film fitted.