If you’re thinking about more challenging rides, some pointers for your internet search:
Chilterns 100 / L’Etape UK – multi-distance one day sportive
Dragon Ride – various distances across the Brecon beacons
Dunwich Dynamo – head to the coast on this classic night ride close to the summer solstice
Etape du Tour – the Queen stage of each year’s TdF
Fred Whitton – a serious day out in the Lake District
Isle of Wight Randonnee
King Alfred’s Way – a multi-day gravel ride either bike-packing or supported (look up John at Wild Cycles and mention the club)
Lombardia
London Brighton London return – multiple routes on the forum
London Cambridge London return – multiple routes on the forum
London Edinburgh London – audax runs every 4 years out of cycle with PBP
London Revolution – a sportive loop of London or the London Orbital audax version
Mallorca 312 – an early season ride
Maratona – a glorious ride around the Dolomites in North East Italy
Marmotte – a classic day in the Alpes
Paris Brest Paris – audax runs every 4 years
Paris Roublaix – cobblestones
Ride London Essex – the annual ride
Ride of the Fallen Leaves – Dulwich Paragon’s annual club ride
Tour of Cambridgeshire
Tour of Wessex – a three day event across Somerset