Hi Annie what you first see when any plant puts up top growth are what is called the cotyledons these are actually part of the seed and serve as a food source until the real or 'true' leaves emerge. These will look like normal tomatoes leaves just considerably smaller. At an inch to inch and a half I'd say you were only seeing the cotyledons.

thank you moon grower - i don't even understand cotyledons but I will leave them - how big are 'tru leaves' and when do i thin them out cos have got loads of cotyledons by the sound of it! Do you just think I should just give this whole growing things a miss - I'm obviously not good enough if I don't know how to follow instructions from a hanging basket from Aldi!

Annie you are doing fine, you are simply learning which we have all had to do :-) The first 'true' leaves to appear will actually be slightly smaller than the cotyledons but, as I wrote, they will look exactly like mini tomato leaves. Don't give up, Aldi are crap at giving good info! I suspect you planted your tomato seeds a little late, for this year you might want to consider buying 6 plants from a garden centre or nursery - but if you do have to do so try growing your own again next year... it is all fun and frequently hit or miss :-)