Waiting for WCA while employer wants me back at work, any advice?

Off work since October (took ages to get crohns diagnosis), Claiming UC since Jan. Referred for WCA end of May (maybe delayed because i was on half pay for a few months), UC50 acknowledged early July, still no assessment date - they said in the journal I should receive an appointment "in a few weeks"

Employer referred me to a decision maker to see if I would keep my job, they said I can have another 6 weeks before I have to go back to them and now I'm feeling pressured into going back to work when I'm not ready, so feeling like I'll return in 6 weeks on 1 or 2 days a week for now (with adjustments that don't contradict my UC50)

Questions:

• Does returning to work part-time before the WCA decision affect getting LCW?
• If my earnings go over the £881/month threshold, does that cancel an already in-progress referral, or does the assessment still go ahead? (although I shouldn't go over this)
• Roughly how long should I expect to keep waiting at this stage?

Any advice appreciated, trying to figure out the best move to balance trying to get support, with trying to not lose my job before I commit to a return date.