I’ve not taken a bike on a train for 35 years ! But if it’s straightforward here (Norwich, Lowestoft, Ipswich area….) it could really broaden the perimeter of day rides open to me….
The services requiring reservations in your area are the London-Ipswich-Diss-Norwich intercity ones and the Norwich-Ely-Peterborough-Nottingham/Liverpool East Midlands Trains. Also the Stansted-Cambridge-Ely-Peterborough-Birmingham ones encourage reservations and get very crowded. The rest, including the coast lines and the Greater Anglia services through Ely or Cambridge, are all turn-up-and-go.
Some guards do enforce the 6-bike limit, so you may have to wait for the next one, which can be annoying on the 1-train-per-2-hours Peterborough-Ely-Ipswich route and cause a diversion to Cambridge if space permits. Other guards are friendlier and allow you to load as many as fit in the space, but take padding if you're precious about the paintwork.