Hi, This is our neck of the woods so I can advise on local beaches etc near Seaview. Don't know about the campsite except it seems like it would have a lot of good facilities etc (it seems very well set up).
Lands End itself is a complete waste of money IMO, but nearby are some beautiful places and they won't be too busy in September. I can highly recommend Sennen beach website here which has a really lovely restaurant as well as surf school, decent loos etc.
The Gurnards Head is a really nice, child-friendly gastropub (nice for lunches especially).
DH has just pointed out that if you have a pushchair, it is only about a 20 min walk along the pavement to Land's End (you can get into the site free if you don't have a car). That way you can see Longships lighthouse and the views etc without getting fleeced for parking etc! Paths are wide and suitable for pushchairs all through the Lands End site.
He also says the Little Barn Cafe is close to the campsite and worth a visit, especially for a cream tea!
Eden Project is about 1 1/2 hrs from here, Heligan a bit further. Both great - Heligan slightly less well set up for pushchairs as I remember, but utterly lovely nonetheless. Eden Project a bit pricy - and wear layers, it is boiling in the tropics biome!
DH now recommending that if you go up to St Austell for both of those, might be worth spending one night up there - maybe en route - to save driving time. Eden is def. a whole day trip, Heligan maybe slightly less (though is 6 years since we went and may be more to see now) - look out for the mossy lady!
Oooh, I'm hankering back for the days when we came down on hols and still did the tourist bit!!
I stayed at Trevedra Farm in June and it was amazing- the views from the camping fields are beautiful. Showers were suprisingly good-better than they look from the outside! There is also a free freezer for your ice blocks. Agree with the advice for Lands End- defo better to walk than drive and pay for car parking. HTH