Lizzie's advice on hand tools is spot on, except she forgets
a good fork and
good secatuers. I would emphasise
good, DIY store own brand is a false economy, I bought my son a spade and the damm thing bends when you try and turn over soil.
Machinery.
Depending on how you do your vegging, what scale it is and what your personal health/fitness is like then machinery may be useful. I have back problems, so try to avoid manual digging, I still do some, but use rotovators. An
american style spade, heart shaped blade and really long "mop" handle gives much better leverage and is back friendly.
Once you take account of how much time you have available is when machinery becomes an option for the fit and healthy.
I note your £ constraints, but patience and caution can allow you to pick up keenly priced kit when available.
Find a local mower repair and sales place. If they are any good they will take old kit as trade ins, or there may be a secondhand trader locally, there you can get quality kit that might look shabby, but is still sound. e.g. Hayter mowers have an aluminum deck (cover above the rotary blades) this lasts forever and a rusty engined hayter may well outlast a new mountfield. I have a hayterette that runs fine on its £10 replacement engine and is pushing thirty years old now.
A petrol engined
strimmer, cheap one, is very worthwhile. I do all the mowing on our allotment site and I can edge the whole site's paths in an hour. At home all the lawn edges take less than five minutes. These things do not care how long the grass is or what it is up against, just be careful of plants and softer items or chicken wire. Under £100 new.
If you are within your own garden and the maximum cable run then
electric kit is very useful, I believe Mantis do an electric version of their tiller. Strimmers, mowers etc are all available in electric forms. The only downsides are that the mowers are usually a bit useless, (blunt & painted, spring-loaded blades) and electrical safety issues.
Petrol rotary mower is always useful and can cope with a little damp grass. If it has a pickup bucket or bag it may clog on longer grass, also might struggle to eject grass without bag/bucket. I have a second hayter with roller and bucket which cost £175 second hand, current equivalent new is circa £600.
Petrol cylinder mower won't cope with long grass, but leaves nice stripes. Rotary with a roller and pickup is more versatile.
Petrol rotovators, I'm a heavy (in both senses) user of these. But they are expensive, heavy and need storage space, fuel servicing etc etc. However, you can dig a whole allotment plot in a few hours. New these are really expensive bits of kit. They are available from hire shops, but a couple of hire's can add up to buying a second hand one. Second hand there is a keen trade in these on e-bay. However watch for a while before bidding and be wary of "bargains".
Two types here, ones that bounce along on the digging rotors and ones that drive along on wheels with the rotors behind. Merry Tiller is the most common of the first type, seek advice from Richard or Clive on this forum on these, I have one that cost mother £60 in the seventies and is still going strong. Howard 350 is the best of the latter types, price/availability/age/spares-choice compromise that is. These are trading at prices around their name. As with all second-hand machinery be wary, find a friend who can help or check stuff before parting with your wonga.
Greenhouses.
Growbag style with plastic cover are OK, but the cover deteriorates very fast and the frame is steel so rusts.
Cheap "
proper" ones are quite often flimsy and will have horticultural glass.
I would say try
http://www.greenhousesdirect.co.uk/ for a good idea of costs and quality compromises and watch your local classified papers for "buyer to dismantle and remove" adverts, sometimes free, though never near me

.
Hope this does not swamp you, but I've got a slack spell here at the mo'.
