Antennas aren't specific to any individual "G" but are optimised towards frequency bands. Some bands are shared between 4G & 5G services, others are specific. This also allows for both the user-equipment and network to always fallback to 4G in the event of 5G not being available for whatever reason.
Capacity improvements are an ongoing process and very much BAU, although specific local plans are very rarely disclosed outside the networks organisation. Your best best is to monitor your local authority planning website for any upgrade works that are requested by either EE or one of their agents. Not all capacity or tech uplifts need build works, but many do.
Quite often the "my places" feature of the online status tool, will also advise on planned outages a short time in advance. Incidentally, those speeds are not uncommon for a rural area without the advantage of multiple sites/sectors covering you.
