Line a 40 x 24cm oven tray that is at least 2cm deep with baking paper, extending the paper beyond the tray.
Combine sugar, golden syrup and water in a large saucepan. Heat and stir until sugar has dissolved. Increase heat and simmer without stirring for approximately 10 minutes, or use a thermometer and simmer until it reaches 150°C.
Remove from heat and stir in the bi-carb. Mixture will foam and rise quickly. Pour into the prepared tray ensuring it covers the base of the tray completely. Allow to cool for approximately 1 hour.
Place chocolate into a heat proof bowl over a saucepan of gently simmering water. Stir until melted. Spread over the cooled honeycomb and scatter the pistachios, craisins and coconut over the chocolate. Allow to cool. Once chocolate has set, drop the tray onto a firm surface and this will break the honeycomb into pieces.