CRT licence ends July, where next?

Registrations run April to March on EA waters you can't just buy 6 months when you want to.
Reduced registration doesn't start on EA waters until September, there is no 6 month registration as such.
Possibly better to trade up to a gold licence runs Jan to Dec cart will refund your old licence from January.
Dont forget much of the anglian system is in flood from October to March and unusable.

If it was me I would go for a gold licence in April come on to EA waters then and leave in September.

If you buy a gold licence cart will refund the part of your canal licence from Jan 1st so you are not licenced twice. The gold will then cover you for the whole of that year on both EA and cart waters.
EA registrations run from April to March apart from the year you can only buy one month or less so it works out expensive if you want to do 3 months cheaper to get a gold.
The only cheap way is to register after September when you get the registration for 50% discount however much of the system will be in flood/on SSA for that period

Take notice of what @loddon says

Last year was a nightmare

SSA 0n 25/10/2019, off on 04/12/2019 = 6 weeks

3 day period with it off then:-

SSA on 07/12/2019, off 07/04/2020 17 consecutive weeks on SSA!

One of the more prolonged periods of the river being shut in recent memory.

2020 was a better year during the main cruising season no SSA between 07/04/2020 and 04/10/2020

However:-

SSA on 04/10/2020, off 12/102020 = 8 days.

SSA on 04/12/2020 and counting.... 13 days so far.

So out of the last 74 days, 23 have so fr been lost to SSA.

When i say cruising season that takes into account The winter works programme; which is about to start, this year it concentrates on the upper half of the river, couple that with a few flood events and it can be tricky to get a decent amount of boating in.

The Great Ouse suffers similar from Bedford to Earith. Downstream of Earith on the Old West, The Cam and the Great Ouse Tributaries tend not to suffer as badly.

It is awful out here - best stay on the canals

If you end up staying for a while on the three C&RT river navigations accessible directly from the Wash via Boston (the Witham, including the Fossdyke from Lincoln to the Trent at Torksey, the Trent from Gainsborough to Shardlow, and the Soar up to Leicester), then you don't need to buy a C&RT boat Licence until you come back onto the canals at Trent Lock (Erewash), Derwent Mouth (Trent & Mersey) or the Leicester Cut at West Bridge in Leicester.

You're covered on all three of those river waterways by buying a Pleasure Boat Certificate [PBC] which is simply a registration certificate costing 60% of the fee for a boat Licence, . . . it's what C&RT fraudulently describe and sell as a ''Rivers only Licence".

Sorry I should have said EA Anglian waters, I think the Mudway might be the same, it's the Thames that is the odd one out. 😷

Surprise, Surprise.
So that leaves The Old West and Ely Ouse as open. Not a good time (as usual) to be on EA Anglian rivers