I found as long as you use the whip plenty you can easily produce enough settlers. Not connecting the iron until you have a few warriors per city (for happines) helps a lot.
The other thing is you only need 4 cities to use all the bonus tiles in the british iles, so I suggest sending 1 settler (with 2 units and 1 worker IMO) off in your boats. Where it goes is up to you, but I would suggest southern africa, where is can get gems, gold, copper, sugar, cows and clams (?). This is possibly an advanced strategy though. [EDIT]You tend to need to gift France 5 gold to get open borders. You can usually get past spain without open borders.