essbee ds1 is currently at respite (with gooseegg) I pick him up in an hour and a half- he's been there since 10am. I pay for it with direct payments. To get them you need to request a care assessment from SS, then (once they've agreed they will help) you ask for dp's. Actually I've written a rather basic introduction to direct payments on my website so rather than write it all out again look here .
What level of DLA do you get? You may be entitled to come carers- unless you earn more than £80 something a week. I can't remember which level of DLA you need though.
Outside of dp's I think you might struggle. Your area might be better than mine but my council has recently shut the one respite centre that would have been suitable for ds- they now have to pay for people to go outside the area. That's the second respite centre that has closed in the last 2 years.
When you talk to ss mention the impact on dd as well. Part of the reason we get it is so we can take ds2 and ds3 out, otherwise they're stuck in all the time.