There are many types of beehive but in the UK it makes sense to start off with a British Standard as it's easier to find parts for. The British National Beehive footprint is 460mm x 460mm. Ideally there needs to be space next to the stand to accommodate the supers while you examine the brood chamber underneath.
Bees can travel for up to 3 miles to find nectar and the plants they forage on changes throughout the season. This means that they can usually get what they need from surrounding gardens, hedgerows, crops, blackberries. You can encourage your neighbours to plant pollinator species and mow their lawns less frequently as this will benefit wild pollinators and your bees.
Anyone can keep bees, there is no law preventing this in the UK. Well managed bees won't cause any bother to your neighbours, they probably won't notice their presence much as bees tend to fly above 2 metres while foraging. A responsible beekeeper will educate themselves by going on a course with their local association and learn how to manage their bees to avoid swarms. Should the worst happen and your neighbour complains about a swarm taking up residence in their chimney, having public liability insurance is very useful. Public liability insurance included with the British Beekeepers' Association membership is well worth the fees. Consider giving your neighbours a jar of honey, they might become your best customers after tasting it!
Each hive will produce 15-30kg of honey a year depending on what's available for them to forage. We harvested more than enough honey for ourselves with some surplus to sell locally.
For us, 3 hives is about the maximum we can cope with in our 15mx 5m garden. They are at the far end but we often get smacked by bees when walking through their flight path but this has never resulted in stings. They are fascinating to watch and have opened our eyes to all the other insects in our garden. Biodiversity has increased immensely in our garden since we started beekeeping. We have loads of bumble bees and hover flies now because we are more conscious of planting pollinator species for them.
Yes because plants need pollinators to produce food. Honey bees are facing threats from parasites and diseases and would likely disappear from many areas without a friendly beekeeper providing a home and helping them stay healthy. Making conditions better for one species of bee actually helps other pollinators to prosper. We plant flowers that pollinators will feed on and avoid any chemicals that might harm them. They don't compete with each other because they feed on different flowers. We've seen a massive increase in biodiversity in the insects we see in the garden since we started keeping bees. We are focussed on keeping the bees as happy and as healthy as possible and in return we get their excess honey and wax.