Off Peak Return - is it suitable for my journey?

Angel747

In December we are going away for 3 weeks.

My plan is to take the train from Plymouth to Heathrow Airport (T3) around lunchtime to get there about 5pm.

My worry is the journey home. If i assume that the plane on the return journey is on time etc, i could book an actual time back, but knowing what the weather has been like the last couple of years, im very aware that there could be a delay.

This is why i was thinking of the off peak return.

So, does this mean i can book seats on the way up on the day we need, then when we return just jump on the train home when we want, providing its during the off peak times? I worry that we wont have allocated seats (dont want to sit in somebodys seats who have booked) although i supose if its off peak then it shouldnt be too busy.

Also (you can tell im not a regular train user) we will have 3 big suitcases with us - are there spaces for luggage on trains?

Thank you in advance for my silly questions x

Edited to add - ive bought a Family railcard, so this should make my tickets a bit cheaper

Quentin

The answer to all your questions is yes

Angel747

Thank you Quentin, might have been silly questions but i like to be sure in my mind before doing anything!

Paul_the_Painter

Just to add tgat train companies will make it clear if a seat is reserved, Some use LCD displays above each seat saying "available" or "reserved" some with headrest covers, so don't panic.