Lammacs have their pros and cons. If you put them on too soon, the lambs are not dry. They do come in bright colours so you can spot the lambs easily. You can also make emergency covers from thick supermarket bags. They can make the difference between losing lambs and them surviving.
I don't know enough about your breeds to be able to say how they will do lambing outside. I always lamb outside - in April mind - and rarely have problems, but we do have an emergency pen set up in the polytunnel in case lambs are born into a blizzard (there's always one....). Note though that lambing outside definitely does not mean just leaving them to get on with it with no care.
February is often a relatively mild month and even up here we sometimes get a week or so of grass growth, but last year we were under a couple of feet of snow throughout the month, so you must have at least a contingency plan for bad weather.
We have small shelters dotted around the place. Some ewes choose to lamb in these and will keep their lambs in for a couple of days. Others will lamb outside but quickly bring the new lambs into a shelter. This works well for the first few days, but then when a newly lambing ewe wants to find shelter, they are all full and this is when problems can arise.
Some of our shelters are properly built, as in the one I posted a picture of in a different thread, but others are simpler. We have one which was thrown up in an emergency but is popular so we have left it. It is a zigzag of boards, with 4 upright stobs, then more boards nailed on as small triangular roofs, just tall enough for the breed of sheep. This means that whichever way the wind comes, there is somewhere to shelter. As well as permanent or semi-permanent shelters, we put old bales around the place, again often in a zigzag, so the lambs can shelter amongst them. Lambs will also shelter against their mothers who make wonderful windbreaks. The ewes themselves will make good use of the sheltering hedgerow you have.
Really the danger period for lambs is after they are born but before they are suckled - once they have a bellyful of milk they are warm and relatively safe. The bond is made with the mother and she will look after her lamb.
It would be worth enquiring from the previous owner whether these ewes have previously lambed outdoors, as past experience would be useful. If they have, then you can rely on them to know what they are doing. If they are used to lambing indoors with full assistance then you will need to build lambing pens under cover. You still have three months to get organised.
It is not usually useful to start interfering once the ewe has started to lamb outside, trying to move her into a shelter, unless you have a full lambing shed set up with individual pens. Ewes will usually have sussed out where they want to lamb a few days or weeks in advance. Some will stick to the plan while others will suddenly have a small panic and move from place to place in case somewhere else is better - they usually end up at their original choice. If you do want to move the ewe and her lambs indoors, it's best to do it once she has cleaned and suckled them, as she will then follow you if you carry her lambs, low down to the ground and preferably bleating for her.
I am anxious about recommending that you just go for it and leave them to themselves to lamb outside. This is because you yourself are inexperienced, so may not know just when intervention is necessary. If they are outside and there is a problem, then you need to be able to get the relevant ewe indoors straight away, without chasing her ten times around the paddock. So perhaps you should be prepared to lamb indoors this year and possibly get them scanned as suggested by bazzais. It's still a good idea to have some shelter around for the lambs when they do go out.