You can generally board your Off-Peak Return ticket at Bristol Parkway instead of Bristol Temple Meads, since Bristol Parkway is an intermediate station on the same route to London Paddington and is located earlier in the journey. This is permitted under the National Rail Conditions of Travel [1] for most Off-Peak tickets.

However, you must check two critical details on your ticket. First, verify the route restriction printed on your ticket or booking confirmation—look for phrases like "Any Permitted" or a named route that includes Bristol Parkway. If your ticket explicitly restricts boarding to Bristol Temple Meads only, or if it is a special promotional ticket, you may not be able to board at Parkway [1]. Second, confirm that the train you plan to board at Bristol Parkway complies with your Off-Peak time restrictions. Off-Peak tickets have specific departure time windows, and these are assessed based on when the train actually departs from the station where you board. A train leaving Temple Meads during peak hours might become an off-peak service by the time it reaches Parkway, but you should verify this matches your ticket's validity.

If you have a seat reservation from Temple Meads, boarding at Parkway means that reservation may not be held, and you may need to find an available unreserved seat instead. When passing through ticket barriers at Bristol Parkway, if the electronic gates reject your ticket, simply show it to station staff—they will normally allow you through once they confirm it is valid for intermediate-station boarding on GWR services.

For a definite answer, check the exact wording on your ticket or contact GWR directly with your booking reference.