* FTSE 100 up 0.2 pct
* Consumer stocks, energy add support
* SSE, Innogy to merge UK retail activities
* Persimmon weighs on housebuilders after update
* M&S shares rise after half-year results (Adds closing prices, details)
LONDON, Nov 8 (Reuters) - Britain's top share index inched up on Wednesday supported by gains among heavyweight consumer and commodity stocks, while housebuilders were dragged lower by a disappointing update from Persimmon.
The UK blue chip FTSE 100 index rose 0.2 percent at 7,529.72 points, while mid caps were flat.
Among consumer stocks that added most points to the FTSE were Unilever and British American Tobacco, up 1.4 and 2 percent respectively, while gains in oil major Royal Dutch Shell and miner Rio Tinto also helped.
Paper and packaging firm Mondi rose 2.3 percent after Morgan Stanley moved its rating on the firm to "overweight" from "equal weight".
Shares in housebuilder Persimmon fell 3.5 percent, the worst-performing on the FTSE 100, after it issued a disappointing trading statement.
Persimmon depressed the whole sector, with Barratt Development, Taylor Wimpey, Bovis Homes, Crest Nicholson and Redrow also falling.
"We continue to see stiffening headwinds for the housebuilders from a softening market climate with a much weaker pricing outlook, rising costs and a loss of confidence in pricing by both buyers and estate agents," Shore Capital analysts said.
Shares in Marks & Spencer rose 1.6 percent at the end of a volatile session after the grocer reported results.
The company posted a lower-than-expected fall in first-half profit and said it would accelerate its turnaround plan and open fewer Simply Food stores than previously planned.
"You've got a slightly weaker UK consumer possibly coming through in one or two of the retailers' results," Hargreaves Lansdown analyst George Salmon said, adding that upcoming results from Halfords and Sainsbury would shed more light on this theme.
Shares in utility SSE slipped 0.8 percent after agreeing to merge its UK retail activities with German energy group Innogy.
SSE also reported half-year figures, which included an 8 percent drop in profit due to weakness in its networks business.
Some analysts were cautious about the merger announcement.
"Although the idea of a spin-off is understandable, we highlight that both businesses vary significantly in outlook and the industry's track record in integrating service and billing systems is poor," analysts at Jefferies said in a note.
"The move could also result in a rebasing of SSE's dividend and impairment for Innogy."
Outside of large caps, Wizz Air dropped 9.3 percent after reporting results, with the focus on concerns over ticket pricing trends.
Wizz Air's CEO also said it was interested in acquiring airport slots at London Luton from failed airline Monarch.
(Reporting by Kit Rees; Editing by Raissa Kasolowsky/Mark Heinrich)