'Bush' means its habit is 'determinate' i.e. it will grow to a predetermined height and then stop. They do not need pruning or pinching out and most need some support. 'Semi-bush' is also 'determinate' but support is essential.
'Cordon' means that they are 'indeterminate'. They will keep on fruiting over a long period. They should be supported on canes or strings. It is best to 'stop' them once they have set up to 5 or 6 trusses. Pinch out the side shoots, that form immediately above a leaf, when they are tiny. Never damage the stem.
Tomatoes for arthritics
As a general rule the less red the tomato the better, i.e. the whites, yellows, oranges and pinks are likely to cause fewer problems. However, some reds, usually with 'sweet' in the name have been bred to have less of the more harmful (to arthritics) acid.
Grow tomatoes as far from potatoes as it is possible. Tomatoes grown under cover are much less likely to be affected than those outside and wet weather in late summer is likely to bring on blightl.
Tomatoes with good blight resistance but not immunity are:
Crimson Crush F1
Rose Crush F1
Cocktail Crush F1
Where to grow
Large varieties ripen better in a cool greenhouse, unless described otherwise. All others will grow outside in sunny sheltered places - weather permitting.