I'm not sure you really need one as the Swedish sport charts are pretty good, once you get used to the funny order. It's a few years since we did the West Coast (I've done it all up to Stromstad) and I don't think any of the harbour entrances present any problems. We used the free harbour guides, available anywhere with local maps as well, and the aerial photos resolved any difficulties. There is a glossary of terms in different languages inside, so the distance to the nearest systembolaget or bastu is easy to work out. It's a lovely coast and almost all of it in sheltered water if you wish, and a lot of interesting places to visit, or just ramble round. A general vistors' guide to Sweden might be helpful.
I doubt that you will find any in-depth coverage of this area, in the form of pilot books in English. As mentioned above, charts are good and they will guide you into build harbours and marinas. However, they are usually not detailed enough to let you safely into the many natural harbours. You will find some sketches of these in the Skanör-Strömstad book related to on the website. Another alternative could be the book "Tre veckor i Bohuslän" edited by the Swedish Cruising Club:
I've got the Norwegian Cruising Guide, but haven't delved through it very far as yet.
I'm thinking of going up that way next year, but I tend to be fairly cautious as to where I go, since I'm single handed. Box moorings and stern anchors are a bit of a nightmare, as are stern buoys. It's all right if there isn't a crosswind, but otherwise with no one on the side to fend off ... no thanks.
The other thing if you're single handed is that you're limited to legs of around 60 miles or so, so you need to do some careful route planning.
The Cruising Association (CA - http://myca.org.uk) runs a yearly seminar on Baltic Sailing, publish a number of Cruising Guides and Harbour guides to the area, also translation guides to make it easy to understand the free harbour guides, their associated web sites and the Swedish met forecasts. All this is run by their 'Baltic Section', about 200 or so members who cruise the Baltic.
Their Baltic section is probably the definitive source for English information on the Baltic, and provides many inputs to keep English language publications up to date on the area. If you're going to spend more than a couple of weeks on the spot, they also have local agents in many harbours, and an email network for posting questions and answers on sailing matters throughout the area. I believe the excellent www.kissen.co.uk website referred to above was compiled by a member.