hi all,new to this but would like to know if now is a good time build a raised bed for veg?

Hi Aaron, and welcome to GOY if you're new to site.
To answer your question, it depends on your soil and what the weather is like. If you are building a raised bed over existing ground, if it's heavy clay it would be best to leave it until later as it will still be very wet and heavy and spring when it's dried out a little is the best time to work it. If you have sandy soil or a good crumbly loam, its not too early. If it looks like more frost is forecast, the frost will help break down lumpy soil that is dug now and left fairly rough.
A raised bed which is boarded at the sides with treated timber, even though it's initially more expensive, is by far the best method. The whole purpose of raised beds is that you avoid ever walking on the soil once it is dug in the first instance. So having a way of keeping the soil in place is better than just making a mounded bed.
Personally I'm a great believer in non-dig gardening, and I've always constructed my raised bed by just roughly forking over the ground, after hoeing off the weeds, and then building the bed on top. I put a thick mulch (at least six inches) of well rotted manure and in the first year just plant things through the mulch. To sow seeds directly, I make small holes which I fill with seed compost and sand and spot sow seeds into this. Works very well.
After that, it's just a matter of adding more compost to the surface each year and leaving the worms to do the rest. You'll find that the soil beneath becomes more and more friable as the worms aerate it. This method emulates nature in which leaves and other debris fall to the ground and gradually build up a deep fertile soil.
If your soil is sandy and easy to rake into a very fine 'tilth', very fine and crumbly, then you should be able to sow most seeds directly into it, including fine seed like carrot. If it's very lumpy and hard to break down, you may initially need to make a shallow drill and fill it with good compost into which you can sow.
The time to sow is when the soil temperature has warmed up. There's no point sowing anything into cold soil as the seeds will just refuse to germinate and even rot. Exceptions to this are things like broad beans which will germinate and grow slowly even in quite cold soil.
If you just watch what is happening in your garden, as soon as new weeds start to germinate and grow you should know that the soil is warm enough for sowing.
I wouldn't bother to sow anything much before mid March at the earliest, but then you could try early carrots (get a variety that is an early and probably stump rooted one), and depending on what you like, early turnips or a quick growing leafy cabbage like April.or Greyhound. The small Japanese white turnips like Tokyo Cross are excellent as you can harvest them in a couple of months from seed before few other things are ready. They are sweet and tasty unlike the traditional stringy yellow turnips you buy in the greengrocers.
Mizuna greens are also excellent for an early cut and come again leafy crop.
If you're impatient to get going and have some large window sills or a small propagator, starting early vegetables in modules is a great way to get ahead of the season. Once they are well established in the modules, most ordinary vegetables can be hardened off by putting the modules outside during the day, and then planted out. Root vegetables in modules are more difficult as you tend to break the tap root when planting out.
Finally, and sorry this has become far too lengthy!, I'd recommend you look at Square Foot gardening on the Internet or get the book. This is a wonderful method for starting off, even though some of the claims for it are a bit exaggerated. The general principle is a really good one though, to get as many different vegetables as possible from a small space.

Well I certainly can't add to that! Well done Bertie - very clear...

ditto:o)