Multi-purpose compost is too strong on its own for the emerging seedlings. You could buy a bag of coarse sand and mix this 50/50 with the compost, it is what I use.

Thankyou Bulba. Now I have another useful tip.

I did write about why we have seed compost and all the verious other compost,
Seed compost has the advantage of being light in texture and will stay moist without being soaked,
if you use any other compost you stand a good chance of the seed rotting due to (a) the compost holding to much water & (b) being to compact for the seed once germinated to push through the compact compost.

Seed compost is just for that "seed's" nothing else,
it will help to retain the correct moisture, heat,and be light enough to allow the young and very tender plant to push through.

Once your tomato plants have pushed through and the first common leave has formed the plant is now needing to be potted on to the next compost that will contain fertilizer to help this very young plant grow,
Until then the plant will get enough food from the seed pod.
If you want tried & tested results use seed composts, this is why all the garden experts say use seed compost.
Now you have the full info its up to you to decide what way you feel is the best way to go.
Regards Dungy.

I always use a multi purpose compost that has been sieved first to remove lumps.
I have never known seeds rot using this method, though I must state I only use peat based composts, not garden centre/DIY store rubbish.
Even if you buy a specialised seed compost from such places, always sieve it first.
I have been using the same batch of compost...it is Humax original...for seed sowing for numerous years. When seeds have germinated and been transplanted I put the compost back into my container and use it for the next lot of seeds.
Saves money that way.

What a lot to think about! Lessons learnt Dungy; and hopefully, memorised. Scrumpygraham, what a good idea to reuse your seed compost. i'm all for it but would never have thought of it in this case.
I'll have a look in Wilco tomorrow as that's where I get most things these days, not being a driver and able to get to a GC easily. I'll check out their stock of not too heavy composts or coarse sand and can't wait to sow the toms when i get home. Lovely and sunny here today and hope it is where you are.Thankyou for giving me answers.