This is what I would do if I were in your position currently......
ok...from being a"non major" problem when your knee was presumably just painful....you have effectively moved up several degrees into a a "priority treatment" position... (and I know the NHS well as I work within it!)...just to clarify the terminology!! Extension = Straightening ability
Flexion = Bending ability
o degrees extension means your leg is perfectly straight...45 degrees from extension means your knee is bent at 45 degrees from straight (like yours!)....90 degrees flexion means your thigh and lower leg are at right angles...and say 140 degrees flexion would be when your knee is bent double to touch the backside!
OK...so your plan of action really ought to be....to go to your local A & E department initially (forget that you have surgery scheduled for June or whenever..) and go through the rigmarole of being probably fobbed off by a triage nurse saying "youve sprained a ligament!" or something similiar. Explain that you know that is not the case and you have been advised (dont say by whom) to seek immediate help due to the probability you have a serious displaced meniscal tear......
DO NOT accept anything less than an appointment at the outptients "fracture clinic" in the hospital...which are usually run twice a week in most average hospitals...this is where you will be able to see a specilist KNEE surgeon (and ensure that is who you are having an appointment made with...NOT a general orthopaedic surgeon)
OK...with any luck you will get an appointment with a knee surgeon at the fracture clinic. If you did then in all probability he/she will see that your injury is classed as "serious" (explain the history of the injury of course) and schedule you an appointment for surgery far sooner than you have it at present.....like within 2 or 3 weeks MAX. They may even arrange for you to have an MRI scan very fast in order to confirm the problem. In my case....(and the fact I was at the time a final year medical student made no difference as I was at a totally unknown hospital where I knew no-one of consequence.....I was in a very similiar state to you..and had been injured for 2 weeks prior to going to the fracture clinic. The knee surgeon was pretty good and got me an MRI within 4 days !!! and had me in surgery about 2 weeks later.
Something I was very grateful for as I seriously believe the time having my leg locked cost me more than the meniscus tear/repair did
By the way...can you limp at all at the minute?? as I couldnt even touch my foot down really...it was agony!!
Also, how are you sleeping? are you propping a pillow under your leg? I was fine for about 3 weeks doing this while I was waiting but my knee became sooo stiff during the 4th week..
Either way...good luck and keep us posted with how your doing