I’ve taken part in two. If you google on NHS and trials, you should be able to find some info.
The first one was the STREAMS trial at Imperial College - they approached me due to lesion activity on MRI, I’d had that MRI after seeing a consultant my neuro rehab doctor referred me to when I said was interested in trials. My stemcells didn’t grow in the lab so that ended pretty quickly. As it was an NHS trial, they did reimburse mileage and fed me and hubby when we had to go in for the day to have stemcells harvested. They also had a special lounge for participants/family etc.
The second was for a spasticity drug. It was an online thingy I saw on facebook and I was rejected immediately after completing the online form… then a nurse called me. It was a drug company phase two trial, so the company paid for taxi journeys to/from the hospital and was happy to pay for lunch/coffee.
Good luck, they are doing HSCT trials for PPMS patients but there’s quite specific criteria to meet - I didn’t