LONDON, May 1 (Reuters) - Britain&aposs FTSE 100 .FTSE index is seen opening 5 points higher, or 0.07 percent, according to financial bookmakers.* The UK blue chip index closed 0.2 percent higher at 6,780.03 points in the previous session after hitting an intraday peak of 6,794.88, the highest level since early March.* Trading volumes are likely to be thin as other stock markets in Europe are clos