Don't know about dissolving pellets. If they do dissolve you would still have to make the solution up in such a way that you know how much fertilizer you have to the gallon and estimate a metre coverage.Why not try it this way!:
You might find it helpful to mark off a metre square with canes on the lawn and weigh out the amount of pellets recommended per metre. If you only do a square at a time its a lot easier to get an even spread although it does take rather longer. . If you have enough canes you can of course lay our several squares at once, or even mark two parallel lines of twine a metre apart and lay canes across a metre apart You only need three canes as after doing each square you just move the back cane to the next square Then measure out the amount of pellets needed for one metre and see how big a handful it is or put about three metresworth in a small container and keep refilling it from the box as you go.. Having produced burnt patches years ago I now use this method though it takes ages. Or you can buy a lawn spreader that has holes you can vary the size of that is supposed to deliver a measured quantity as you push it along but you have to calibrate it first for the size of granules you have. Its all a bit of a fiddle but the lawn stays green....

Which product have you bought? Lawn feeds are usually not used before March, and most of the packs actually say April, so its way too early to feed the lawn anyway.

If the lawn feed includes a moss killer and/or weedkiller, that might be the cause of the bare patches - uneven or over application can cause the same problem, but you usually know when you've done that because where there's too much of it sitting on the grass, it goes dark brown or black.

As for dissolving the pellets or granules, no, do not do that - they come in that sort of formulation so they break down slowly, over a period of (usually) 6-8 weeks, releasing nutrients such as nitrogen slowly - if you dissolve them then apply, you'll be overdosing because all the nitrogen will be released at once.

You can buy liquid lawn food that you mix in a watering can - but its too early for that as well.

You will burn your grass/plants if you dissolve pellets all at once. You have a slow release fertilizer & that's how it's intended to be used. It releases just a bit as it slowly dissolves with each watering.

What exactly is "spring feed" in this context? We don't use such terminology here in the desert. Is it a high nitrate fertilizer which dissolves and acts quickly in low temps, such as 21-7-14? Or is it a slow release organic or ureaform type intended to be activated by soil bacteria as soon as the soil is warm enough to wake them up?
Whichever kind, even application is essential, and it takes some skill to do that by hand. If lacking that skill, I would recommend using some kind of fertilizer spreader.

Tugbrethil: "Spring feed" refers to when plants just wake up from winter dormancy. It's like "Breakfast" for plants. Getting them off to good healthy start - like having a bowl of Wheaties, fruit, toast, orange juice, etc.

Tugbrethil: that's why I asked what product Monkey has got - all 'spring' feeds sold for lawns in the UK are actually spring and summer feeds, things like Evergreen Extreme, and none is intended to be used before the end of March, with a repeat treatment six weeks later with most of them. There is no product intended for use just in spring, unless Monkey's got hold of some product from overseas... the definition of 'spring' in this case means April, March at a pinch if the weather is mild, particularly in the southern half of the UK, but not further north.

wow thanks people, i will digest all this glorious info nearer the time, one thing i have gleaned is not to dissolve the pellets,

Weed and feeds are designed to kill off daisies and dandelions etc as well as moss but they need to be growing and that is partly why you wait until April. Grass is lots of small plants and while the weather is still cold you don't want to encourage growth. The die bag is burning due to lack of rain or watering. It needs to rain within two days. I have never used pellets.