Linda,I would phone Thomas Cook airlines as I have known the travel agents to not pass the info on to the airline.
I flew with Thomas Cook last month and I was sat near a couple who I remembered from 3 years ago!
The man had requested a medical seat as he had plates in his leg after an accident and all was well on the way there.He was in seat 12A which had no seat in front but was 1 row back from the exit row.On the way back he was allocated an ordinary seat which he couldnt sit in and he spent the flight(From Turkey) Standing apart from take off and landing wher he sat in the seats the crew use!
If you phone the airline they will ask you for details of your condition and allocate you a suitable seat.The agents are not always reliable.The phone number is 0844 855 0515.Its best to phone at 9am as the office opens.

hi,when i picked up our tickets there was nothing on them to indicate medical seats so i phoned thomas cook and she said we are down for medical seats but would not know where till check in, anyway thanks for your help linda

Linda you can still phone Thomas Cook airlines up until 7 days before departure,at least they will confirm you have been allocated a medical seat.

Hi Linda,

In my experience (one trip only!) things worked out very well on the outbound trip - my mother was seated in the seat that Jaytrip refers to - but on the way back from Tenerife it was chaos. It seems as if you are very much in the hands of the local check-in staff on your return flights and if somebody checking in ahead of you makes a fuss about not being seated together etc there's a good chance that they'll give them your seats in order to get rid of them. My advice would be that the odds are you will have been allocated suitable seats on both the outbaound and inbound journeys but on the inbound journey, make yourself known to the TC reps as soon as you arrive at the airport and to try and arrive early in order to get in the queue early. It seems to be the only way to guarantee that you will get the seats pre-allocated to you.

SM