Buying Hybrid 4 mattress

Dear John & Ryan,
We are in the process of wanting to change our old mattress which is a medium to firm spring, orthopaedic mattress. We have had it for about 18 months having got it second hand due to very limited funds at the time. Of late the heaviest of the two of us has found it particularly painful sleeping on their side due to being able to now feel the springs. The mattress feels too firm for either of us and neither of us have been sleeping well for some time.
We tried a few beds in shops and then came across your website which was something of an eye-opener with regard to choosing the right mattress. In one shop we were told the choice of mattress would lie with the one who slept on their side rather than the one who sleeps on their front which was not great news for the front sleeper. No-one mentioned weight in relation to how a mattress would feel despite our very different heights and weights, one being 6ft 2 and weighing 16 stone 9 and the other 5ft 4 and weighing 9 stone. It was about how you slept.
The mattress that got both our attention whilst looking in the shops was Tempur Cloud Sublime, also known as Tempur Delux 22. We were told that soft, medium and firm do not mean that a bed lacks support. This mattress felt like lying on a cloud, without the pain we both had been feeling of late, but with a great deal of support. We walked away however because we had not planned on spending over £1,500 on a mattress neither could we despite our funds not being as limited as previously.
We then came across your website and your Hybrid 4 mattress which you say is like the Tempur Cloud Platinum or Tempur Cloud 27 at £960 for a double mattress instead of over £1,500. However we then read that due to the weight of the Hybrid 4 mattress we would need to board over the slats we have at present in order to support the mattress as a firm base is needed. We live in a first floor flat and we opted 18 months ago for a cheap slatted base, without the much needed storage we need, because of access and limited space around the bed for drawers.
We looked at your bases and the ottoman base, plus headboard, for £585 got our attention as it is in two halves. Any ottomans we saw previously were either too big or had not so good reviews. Your ottoman base was different. However, this again would increase our costs to over £1,500 though admittedly for everything – a cloud-like mattress, an ottoman base and headboard – everything we ideally want and need.
We then began looking at mattress toppers to extend the life of our present mattress reducing the pain and giving us more time to save up in the meantime for the whole package.
So to our questions.
1. Is the Hybrid 4 a mattress you would recommend for our requirements?
2. Would we be able to buy the Hybrid 4 topper separately and use it to extend the life of our current mattress, not putting our finances under too much strain, until we saved up more to buy the Hybrid 4 base mattress and ottoman base and headboard or would we have to buy the Laygel Hybrid mattress topper for £275, knowing once we got our new mattress we’d never use it again?
3. Would it be better to buy the mattress, board up our slats and get the base at a later date as it won’t cause significant damage to the mattress not having a firmer base for say 12 months?
Our budget at present is £1000. We could do with spending less but what we can’t do is keep things the way they are with our current mattress.
Your help and advice would be most appreciated.
A+B