Looks like we might be heading to Blanes - south end of the beach is nudist and well established and there's a big family orientated campsite in walking distance.  Looks like a bit more of a tourist town than I'd normally go for but beach and kids entertainment will hopefully compensate for that!

We'll hire a car also so might hopefully get out to explore other beaches in the area - Canet De Mar doesn't seem far!

If you head down to Canet its about 30 to 45 minutes by car, depending on the traffic on the N11.
Once past Calella the beaches get narrower and there is a nice cove below the lighthouse.
Drive on past San Pol and the beaches are predominantly naturist but a bit narrow, parking for these is on the road side.
Drive on till you reach the traffic island with the boat on it, turn right towards the Dia supermarket, park on the waste land opposite. Walk to the left facing the sea and go through the underpass, once through turn left past La Rocca bar. most of the beach after this point is naturist, if you keep walking to the rail tunnel the beach becomes more cove like, this is where you find many regulars and locals. This is a good beach for kids as its quite spacious, can be busy at weekends but quiet in the week even in high season. If you turn right out of the underpass there are a couple of beach bars where boats and paddle boards can be hired, this bar is run by the campsite across the road El Globo Rojo her chalets are for hire as well as camping.
Canet de mar is further down the road, this is a nice village with numerous bars and restaurant full of locals and not to many Brits about, unlike the near by Calella.
There are more naturist beaches beyond Canet towards Mataro. These tend to be wider and busier than the ones I frequent.
I hope you make it down there and enjoy the area as much as my family and I have over the years.

Thank you everyone for the info, it's helping with my procrastination's!

I think a naturist resort isn't right for us at the moment mainly as we have 1 child who is 6 so a more family resort is needed to find holiday friends for him.  I'd also be happy with just naked beach time although I do like the idea of a naturist resort purely for the more non judgemental attitude - El Templo naturist campsite looks good but is too much of a hike from Girona airport

At the moment we're trying to decide when to actually go, first thought was last week of May to avoid the inflated school holiday prices.  If we do that, wondering if Catalan /Costa Brava area will actually be warm enough, seems average temps are only high teens.  So alternative could be the Costa Del Sol, Balearic or Canary Islands.

Second option which is seeming more likely at the moment would be end of July, in which case Costa Brava / Blanca would be better.

We like the mobile homes on the campsites as they give a hotel vibe and facilities without actually being confined to a living in a hotel room

If you're thinking of the Canaries and you don't want to stay at a naturist 'resort' ie Charco del Palo in Lanzarote you could always stay in Playa Blanca which is in walking distance of the beaches at Papagayo, albeit about half an hour walk to Caleta del Congrio which seems to be 'the' naturist beach. That said, the far end of Playa Mujeres is naturist, which is slightly closer.
The other alternative is Fuertevenura where there are a lot of beaches that are naturist, or stay in Maspalomas in Gran Canaria where the naturist beach is quite close.
Hope that helps