Transponders - confused please help ?
 

Can someone please help with explaining my options with which transponder to purchase. I will be starting off in 2wd but may add 4wd at a later date.

Just checked my soon to be club (Coventry model car club) and they have posted this message:

CMCC are changing over to RC4 at the first round of the summer series on 6th April, all AMB or Mylaps PT’s will work with this system with no guarantee that MRT’s will work.
Summer series has been split this year with a 4 round astro series( all Classes on the Astro) and a 4 round Dirt Series(1/8th on the dirt and 1/10th on the Grass), dates as per the club calendar.

You want a harry (hybrid) from bbktiming :)

PT's
 

The best option to go for is the AMB mylaps 'Harry' transponder, it works on ALL AMB decoders bar the rc20, so you can use it on RC2, RC3, RC4 decoders. or the VERY slightly cheaper option is the old amb PT. Take a look at the table I have added to the post you want the 4th one from the left in the table, or the cheaper old one is the 3rd one

get a new MRT transpoder, £50 and works on rc3 and rc4

Yup, our club just went from rc3 to rc4, my mrts worked on both.