Will it be OK as is? Absolutely.
I would do things slightly differently, but I was weaned on such brews in England, and my tastes are probably a bit different than yours.
I'll tell you what I would do different and why, but don't take it as a criticism. There's no reason whatsoever that you should like brews the same way that I do.
First, the grain bill:
I would leave out the cara-pils. The Maris Otter and crystal, combined with the yeast and my suggestions for a different mash provide plenty of body, and I consider that extra head is a waste of space in the glass.
I would also leave out the chocolate. I have tried it to add some color, but I found it added too much flavor that I found it was atypical and overpowering.
According to Designing Great Beers (Ray Daniels) some use black malt or a small amount of dark crystal (120L) to add color. (I have never tried the black malt, and have not really liked the dark crystal, but it was less obtrusive than the chocolate.)
With 8 lbs Maris Otter, I like about 8 oz Crystal 60, but could increase it to 12 oz.
I occasionally use 8 - 12 oz turbinado (sugar in the raw) to lighten the body a bit. I only do this for beers to be consumed in the summer.
Next the mash.
When I learned to brew English beers, I learned to use a mash thickness of 1 qt per lb, and to mash at 150 - 152F. This always worked well for me.
When I joined this forum, I found that most people recommended a mash thickness of 1.25 qt per lb. I tried this thinner mash and it resulted in a very thin tasting beer. I tried increasing the mash temperature to 154 - 156, and it made virtually no difference, so I went back to the thicker mash and lower temperature (which according to Daniels is traditional for English bitters). If you want to try the thicker mash with Beersmith, you need to define a new mash profile..
Your hop additions are very similar to mine, and the 1968 (or WL002) are as good as you can get.
The only other thing I do different is the carbonation rate. I like to keep it below 1.5 volumes of CO2, and serve at ideally 57F, but that varies according to my cellar temperature.
That's a great recipe for your first attempt.