I am about to apply for a retirement visa having satisfied both the age and funding level requirements, however, my plan is to do quite a bit of travelling using Thailand as a base.

Is there any restriction on the number of trips I can do within a specified time period with this visa ?

Hopefully, it's just a matter of getting the stamp and I am free to enter and leave the country as often as I like ?

If you mean an OA visa applied for in your own country, and not an extension of stay on a pre-existing O visa on the grounds of retirement, then you can enter and exit an indefinite number of times during the period that the visa is valid, that is, anytime before the date specified 'use by dd/mm/yyy' on the visa stamp.

You will be getting an extension of stay not at a visa. You will then get a multiple re-entry permit that will allow you to leave and enter the country as many times as you want.

ok, thanks for the info